This invention relates generally to the field of torquing tools and, more particularly, to power or manually driven torque wrenches capable of measuring an amount of torque placed on a fastener.
Wrenches for placing a torque on a bolt or the like which are hand operated or power operated and include means for monitoring the torque are well known. Several U.S. patents describe such wrenches, for example, U.S. Pat. No. 3,683,686 to Sergan, U.S. Pat. No. 3,745,858 to Biach and U.S. Pat. No. 4,665,756 to Snyder all of which are assigned to Raymond Engineering, the assignee hereof.
Torque wrenches which utilize electronic strain gauges are disclosed in various patents including U.S. Pat. No. 4,549,438 to Grabovac et al. This patent discloses a torque wrench having dual reaction arms and strain gauges mounted thereon. When the wrench is operated, the strain gauges output a signal to a bridge circuit and comparator which, in turn, provides output for a digital readout. Also, U.S. Pat. No. 4,876,159 to Snyder et al., also assigned to Raymond Engineering, discloses a dual mode torque wrench for torquing fasteners. This wrench discloses a single reaction arm whereon strain gauges are mounted for providing input to a circuit for displaying torque applied to a fastener. While all of the above-described devices may be used for torquing a fastener, all of these devices pose a problem with respect to use in confined spaces and around conduits, particularly flexible or rigid conduit which are joined together with fittings.
Torquing devices used for simply tightening bolts in confined spaces and disposed on conduit are well known. U.S. Pat. No. 4,562,757 discloses a ratchet wrench which includes a hinged socket. U.S. Pat. No. 3,535,960 shows a power driven tubing wrench having slots for use on tubing. U.S. Pat. No. 4,562,757 to Furey discloses a ratchet wrench having a hinged socket and teeth for engaging a ratchet and thereby moving the socket for tightening or loosening. U.S. Pat. No. 4,928,558 to Makhlouf provides a torque wrench which has a gear train for torque multiplying and an outwardly extending reaction arm which engages a fixed object such as a pipe for preventing rotation of the device while torquing a bolt.
However, none of the above discussed patents disclose a device which provides a means for measuring the torque placed on a fastener. In addition, there continues to be a need for improved, economical torquing devices for tightening fasteners in confined spaces, particularly nuts disposed on conduit such as flexible or rigid tubing.